HARDLY WATER-PERMEABLE CIVIL ENGINEERING SHEET

PROBLEM TO BE SOLVED: To provide a hardly water-permeable civil engineering sheet having biodegradability. SOLUTION: The hardly water-permeable civil engineering sheet which is constituted by laminating a sheet satisfying the following (b): a shading sheet which consists of biodegradable fibers and has a shading rate of at least 80% and an air permeability of at least 10 cc/cm2/s, on a sheet satisfying the following (a): an air permeability/water permeability controlling sheet which is made by the weaving and the heating contraction of the biodegradable fibers having a tensile strength of at least 3.0 cN/dtex, a boiling water shrinkage ratio of at least 10%, and a total fineness of not more than 1,000 dtex and which has a hydraulic conductivity of under 1×10-2, an air permeability of at least 0.20 cc/cm2/s, and an opening diameter (O95) of under 0.1 mm, has a tensile strength of at least 500 N/5 cm, a hydraulic conductivity of under 1×10-3cm/s, an air permeability of at least 0.18 cc/cm2/sec, and a strength retention of at least 50% after being exposed for 500 hours in a sunshine weather resistance test. COPYRIGHT: (C)2006,JPO&NCIPI